Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L27/00—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Compositions of derivatives of such polymers
  • C08L27/02—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Compositions of derivatives of such polymers not modified by chemical after-treatment
  • C08L27/04—Compositions of homopolymers or copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by a halogen; Compositions of derivatives of such polymers not modified by chemical after-treatment containing chlorine atoms
  • C08L27/06—Homopolymers or copolymers of vinyl chloride
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L51/00—Compositions of graft polymers in which the grafted component is obtained by reactions only involving carbon-to-carbon unsaturated bonds; Compositions of derivatives of such polymers
  • C08L51/003—Compositions of graft polymers in which the grafted component is obtained by reactions only involving carbon-to-carbon unsaturated bonds; Compositions of derivatives of such polymers grafted on to macromolecular compounds obtained by reactions only involving unsaturated carbon-to-carbon bonds
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L83/00—Compositions of macromolecular compounds obtained by reactions forming in the main chain of the macromolecule a linkage containing silicon with or without sulfur, nitrogen, oxygen or carbon only; Compositions of derivatives of such polymers
  • C08L83/04—Polysiloxanes

Definitions

• This invention relates to a notched-impact-resistant polyvinyl chloride (PVC)-moulding composition, based on vinyl chloride polymers and impact-resistant modifiers, which contains specific polysiloxanes and optionally conventional additives and auxiliaries and is distinguished by an improved processibility and by reduced shrinkage of articles produced therefrom.
• PVC polyvinyl chloride
• notched-impact-resistant PVC moulding compositions or of the semifinished products and finished articles produced therefrom not only depends considerably on the processing operation, but also on the composition and on the type of the impact-resistant modifier which has been selected.
• Factors which play a significant role during processing and in the assessment of the finished article are the following, for example: rheological behaviour, output capacity, homogeneity and charge uniformity of the finished articles, toughness or notched impact strength, surface quality and ageing behaviour.
• Shrinkage after storage under heat also plays a significant part, in particular in profile extrusion. Therefore, the most varied moulding compositions are known with respect to processing behaviour and final quality and they require individual processing and exhibit different utility characteristics.
• Such notched-impact-resistant PVC moulding compositions are primarily processed extrusion into profiles or sheets. During this operation, the moulding composition is strained both by the necessary processing temperature as well as by the shearing effect occurring during extrusion. It is known that the various PVC moulding compositions which are composed according to the most varied formulations behave differently with respect to their processing during extrusion and that there is an individual, optimum processing range for each moulding composition. If these optimum processing conditions are changed, for example, by an intended increase in the output capacity, an increase in the temperature, or friction, or also unforeseen disturbances, discrepancies are usually observed in the level of mechanical values, in the quality of the surface and also in the residual stability.
• a further problem in the extrusion of profiles from notched-impact-resistant PVC moulding compositions relates to manufacturing the semifinished product (profile) continuously leaving the extruder under as low internal stresses as possible.
• profile semifinished product
• Even pure homo-PVC receives an orientation during the passage through the extrusion tool and during extrusion, due to its structure and to the processing factors.
• the stresses which are frozen in after the hot profile has been quenched are re-released where there is an increase in temperature, in particular in the range of the glass transition temperature, and they are expressed in a measurable shrinkage value of the profile. This shrinkage behaviour naturally impairs the usefulness of such profiles in a great number of areas.
• the shrinkage tendency is appreciably increased by the use of impact-resistant modifiers and as a result of the two-phase nature resulting therefrom.
• pure rigid PVC exhibits shrinkage values of from approximately 1 to 1.3%, measured on 20 cm long profile pieces which have been annealed for one hour at 100° C.
• the shrinkage values may increase up to 2% (measured, for example, on a framing profile intended for the production of windows).
• notched-impact-resistant PVC moulding compositions may be considerably improved by adding specific polysiloxanes. This is seen in the fact that, despite a temperature increase and increased friction during extrusion, there is no decrease in the notched impact strength or only a weak or delayed increase occurs.
• an impact-resistant PVC moulding composition having a 6% EVA content already exhibits clear indications of a reduction in the notched impact strength during extrusion at composition temperatures of from 180° to 185° C.
• the reliable processibility may be extended to approximately 200° C. and thus the sensitivity to fluctuations in the processing conditions may be substantially reduced.
• the reduction in the tendency towards loss of strength is also exhibited in the strain time of a PVC moulding composition based on EVA/PVC at a constant temperature.
• the strain time on a rolling mill may be substantially increased before there is a reduction in the notched impact strength.
• a clear reduction in energy consumption occurs during extrusion when PVC moulding compositions modified with specific polysiloxanes are processed.
• the notched-impact-resistant PVC moulding compositions containing polysiloxanes also exhibit an improvement in the shrinkage behaviour of profiles produced therefrom.
• the shrinkage value is from 0.3 to 0.5% lower in comparison to that of moulding compositions which are free from polysiloxanes but have otherwise the same formulation and processing parameters, i.e. it is reduced, for example, from 1.8 to 1.4%.
• polysiloxanes used according to the invention produce the effects described without an influence on the molecular weight within a wide range which has been observed.
• the type and structure of the siloxanes and the concentration in the PVC moulding composition are probably essential for the magnitude of the effects observed.
• the present invention provides a notched-impact-resistant polyvinyl chloride moulding composition having a low shrinkage value and based on vinyl chloride polymers and impact-resistant modifiers, optionally containing conventional additives and auxiliaries, characterised in that the moulding composition contains a total of from 0.01 to 5% by weight, preferably from 0.1 to 2.0% by weight, based on the total of vinyl chloride polymer and impact-resistant modifier, of liquid polysiloxanes having viscosities of from 20 to 100,000 cSt and/or solid polysiloxanes having molecular weights of from 20,000 to 500,000.
• the liquid polysiloxanes preferably have viscosities of from 60 to 50,000 cSt.
• Polydimethylsiloxanes and polymethylphenylsiloxanes are preferred polysiloxanes.
• Polysiloxanes which are particularly preferred are the following:
• liquid polydimethylsiloxanes having methyl terminal groups in the viscosity range of from 20 to 100,000 cSt
• polydimethylsiloxanes having vinyl end groups and molecular weights of from MW 40,000 to 100,000.
• the moulding composition according to the invention is composed of the following:
• the components (a) and (b) may be partly or completely chemically linked together in this two-phase moulding composition and may be, for example, in the form of a graft polymer.
• Vinyl chloride polymers which are suitable include the following: homopolyvinylchloride, copolymers of vinylchloride with up to 20% by weight of ethylenically unsaturated comonomers, graft polymers of vinylchloride, in particular having the impact-resistant modifiers as the graft base, and mixtures of these polymers.
• Impact-resistant modifiers which are suitable include the following: elastomeric polymers or polymers containing elastomers, such as ethylene-vinylester, in particular ethylene-vinylacetate copolymers, chlorinated polyethylene, acrylate rubbers, ethylene propylene rubber or ethylene propylene terpolymers, ethylene acrylester copolymers, polybutadiene and copolymers or graft polymers of butadiene with, for example, (meth)acrylonitrile, styrene and methyl acrylate. Ethylene-vinylacetate copolymers and chlorinated polyethylene are preferred.
• elastomeric polymers or polymers containing elastomers such as ethylene-vinylester, in particular ethylene-vinylacetate copolymers, chlorinated polyethylene, acrylate rubbers, ethylene propylene rubber or ethylene propylene terpolymers, ethylene acrylester copolymers, polybutadiene
• Chlorinated polyethylene is produced, for example, by chlorinating high-molecular weight low pressure polyethylene having densities of from 0.940 to 0.965. It has chlorine contents of from 28 to 42% by weight and has a reduced specific viscosity of from 1 to 5 dl/g (measured in 0.5% by weight solution in tetralin at 135° C.).
• CPE chlorinated polyethylene
• PVC/CPE moulding compositions is described, for example, in German Pat. Nos. 1,236,774; 1,045,089; 1,109,365, and in German Auslegeschrift Nos. 1,469,990 and 1,266,969.
• Ethylene-vinylacetate copolymers which are suitable contain from 25 to 60, preferably from 35 to 50% by weight of vinylacetate and have molecular weights of from 20,000 to 500,000.
• Moulding compositions which are preferred are composed of the following:
• preferred moulding compositions are based on mixtures of (a) polyvinylchloride and (b) a graft polymer of the following:
• Moulding compositions having a content of ethylene-vinylacetate copolymer of from 4 to 8% by weight are particularly preferred.
• the impact-resistant modifiers are added in pure form as blocks, granules or powder, and, for example, talcum, chalk or silicates may be contained as additives to improve pourability.
• a variation which is frequently used comprises initially subjecting the rubber-elastic polymers to a graft polymerisation process, preferably with vinylchloride, and optionally also with other monomers, and introducing the resulting graft polymers into the PVC moulding composition.
• additives and auxiliaries which may be contained in the moulding composition are the following, for example, corresponding to the requirements in each case: stabilizers, lubricants, pigments, dyes, fillers, flow aids and flameproofing agents.
• a conventional component of PVC moulding compositions comprises, for example, stabilizers against thermal and ageing-conditioned decomposition, such as barium/cadmium- or lead salts, tin compounds and/or epoxy compounds as are usually used in PVC technology.
• stabilizers against thermal and ageing-conditioned decomposition such as barium/cadmium- or lead salts, tin compounds and/or epoxy compounds as are usually used in PVC technology.
• lubricants may be used to improve the flow behaviour, such as, for example, metal soaps, higher fatty alcohols, fatty acid glycerine esters, synthetic waxes or paraffin and optionally flow aids based on polyacrylate or styrene/acrylonitrile.
• the moulding composition according to the invention may be produced, prepared and mixed or processed according to the most varied methods.
• the PVC moulding composition is initially produced such that the individual components are mixed thoroughly in high-speed mixers, optionally with a temperature increase. Mixtures of this type may be directly supplied to the different processing processes (dry-blend processing) or they may pass through a granulation stage before the next and final moulding operation.
• Polyvinylchloride and/or polyvinylchloride copolymers with ethylenically unsaturated compounds are mixed together with the pulverulent or granule-form impact-resistant modifier, optionally with crushing, with the polysiloxane compound and the conventional additives (stabilizers, lubricants, fillers and pigments) and are directly processed (dry-blend process) or are further processed via the granulation stage; mixtures produced on rollers, kneaders or screws are further processed into a granulate or directly using a calender.
• the process described here relates to all impact-resistant modifiers, but in particular to ethylene-vinylacetate copolymers, chlorinated polyethylene and acrylate polymers.
• Graft polymers of vinylchloride on ethylene-vinyl acetate copolymers are mixed in a high-speed mixer, optionally with the admixture of homo-PVC to adjust the necessary EVA concentration, with the addition of the polysiloxanes and further processing auxiliaries, and are further processed. It is also possible to process such mixtures using rollers, kneading machines and internal mixers.
• the polysiloxanes are added in the necessary quantities to the graft mixture and they pass through the polymerisation process. After the reaction has finished, they are in the graft polymer which is further processed according to 1 or 2.
• the preferably liquid polysiloxanes are added to the PVC suspension or dispersion and are homogeneously distributed with stirring.
• the polysiloxanes are drawn onto the PVC grains and are in the PVC graft polymer after isolation.
• Pulverulent mixtures which are ready for processing (dry-blends) or processing-ready granules are processed into semifinished products or finished articles using extruders, injection moulding machines or blowing machines as known in the art.
• extruders injection moulding machines or blowing machines as known in the art.
• moulding compositions using rollers, presses or moulding calenders.
• the moulding compositions according to the invention are distinguished by their quality with respect to their mechanical value level and their behaviour in ageing and weathering processes and they are suitable for the most varied areas of use. Extruded profiles are primarily produced therefrom, but the moulding compositions are also processed into injection-moulded articles or calendar films. While the notched-impact-resistant PVC moulding compositions which are provided with light-stable impact-resistant modifiers are used for internal purposes, in this case, including in particular articles of furniture and building parts, pipes, films and packing materials, the systems having the highest weather resistance are used for external purposes, in particular in the building industry.
• Light-stable, notched-impact-resistant PVC moulding compositions based on ethylene-vinylacetate copolymers according to the invention are particularly suitable above all in the production of window profiles, facing panels, benches for parks and sport stadiums, gutters and downpipes, road restriction posts and motorway noise control constructions.
• polysiloxane A polydimethylsiloxane having methyl terminal groups and a viscosity of 20 cSt.
• polysiloxane B polydimethylsiloxane having methyl terminal groups and a viscosity of 140 cSt.
• polysiloxane C polymethylphenylsiloxane having methyl terminal groups and a viscosity of 350 cSt.
• polysiloxane D polymethylphenylsiloxane having methyl terminal groups and a viscosity of 1,000 cSt.
• polysiloxane E polydimethylsiloxane having OH terminal groups and a molecular weight MW of 90,000.
• polysiloxane F polydimethylsiloxane having vinyl terminal groups and a molecular weight MW of 500,000.
• suspension PVC K-value 65
• EVA ethylenevinylacetate
• EVA ethylenevinylacetate
• di-n-octyl tin mercaptide di-n-octyl tin mercaptide
• Example 1.2 Composition as in Example 1.1+1.5 parts by weight of polysiloxane A, production of the test bodies and test as in Example 1.1.
• Example 1.3 Composition as in Example 1.1+1.0 parts by weight of polysiloxane B, production of the test bodies and test as in Example 1.1.
• Example 1.4 Composition as in Example 1.1+1.5 parts by weight of polysiloxane C, production of the test bodies and test as in Example 1.1.
• Example 1.1 1.5 Composition as in Example 1.1+0.5 parts by weight of polysiloxane C, production of the test bodies and test as in Example 1.1.
• Example 1.1 1.6 Composition as in Example 1.1+1.5 parts by weight of polysiloxane D, production of the test bodies and test as in Example 1.1.
• Example 1.1 Composition as in Example 1.1+1.0 parts by weight of polysiloxane E, production of the test bodies and test as in Example 1.1.
• Example 1.8 Composition as in Example 1.1+1.5 parts by weight of polysiloxane F, production of the test bodies and test as in Example 1.1.
• Notched impact strength (kJ/m 2 ) according to DIN 53 453 at 23° C., depending on the rolling temperature, measured on test bodies which were produced from the pressed plates of Examples 1.1-1.8.
• the addition of the polysiloxanes A-F results in an expansion of the processing temperature range of from 10° to 15° C. with outstanding notched impact strength values. It may also be seen from Table 1 that the expansion of the processing temperature range does not depend on the molecular weight of the polysiloxanes A-F.
• VEVA vinylchloride-EVA-graft polymer
• K value 68 400 parts by weight of suspension PVC (K value 65), 25 parts by weight of solid barium/cadmium stabilizer (at least 10% Cd content), 10 parts by weight of epoxidised soybean oil, 5 parts by weight of organophosphite, 3 parts by weight of oxystearic acid, 3 parts by weight of wax ester, 30 parts by weight of white pigment (titanium dioxide, rutile type) and 30 parts by weight of filler (coated calcium carbonate) are prepared in a heating-cooling mixer (1500 r.p.m.) by the method which is conventional for rigid-PVC-dry-blends.
• a heating-cooling mixer (1500 r.p.m.
• Example 2.1 15 parts by weight of polysiloxane A are added to 1106 parts by weight of a PVC moulding composition, composed as in Example 2.1, and are prepared, rolled, pressed and tested, as described in Example 2.1.
• polysiloxane C 2.5 10 parts by weight of polysiloxane C are added to 120 parts by weight of a VCEVA commercial product (EVA content 50% by weight, K value 75), 880 parts by weight of S-PVC (K value 65), stabilizers, lubricants, pigment and fillers as in Example 2.1, and are prepared, rolled, pressed and tested as described in Example 2.1.
• VCEVA commercial product EVA content 50% by weight, K value 75
• S-PVC K value 65
• Notched impact strength (kJ/m 2 ) according to DIN 53 453 at 23° C., depending on the rolling temperature, measured on sample bodies which were prepared from pressed plates of Examples 2.1-2.5.
• the expansion of the processing temperature range by from 10° to 15° C. is also achieved by adding the polysiloxanes A-F to known commercial vinylchloride-ethylene vinylacetate graft polymers (VCEVA) in a formulation which is conventional in practice.
• VCEVA types having a different EVA content may be used to adjust the required modifier content.
• Example 2.6 2.8 15 parts by weight of polysiloxane A are added to 1015 parts by weight of a PVC moulding composition, composed as in Example 2.6, and are prepared, rolled, pressed and tested, as described in Example 2.6.
• Notched impact strength (kJ/m 2 ) according to DIN 53 453 at 23° C. depending on the rolling duration at 175° C. rolling temperature, measured on test bodies which were produced from pressed plates according to Examples 2.6-2.11.
• Example 2.13 1,000 parts by weight of a VCEVA commercial product (EVA-content 6% by weight, K value 69), stabilizers, lubricants, pigment and fillers as described in Example 2.12, are prepared as described in Example 2.12. In each case, 110 g of this PVC moulding composition (Comparative Example) are rolled, pressed and tested as described in Example 2.12.
• VCEVA commercial product EVA-content 6% by weight, K value 69
• stabilizers EVA-content 6% by weight, K value 69
• lubricants pigment and fillers
• Notched impact strength (kJ/m 2 ) according to DIN 53 453 at 23° C., depending on the rolling duration at 185° C. roll temperature, measured on test bodies which were produced from pressed plates of Examples 2.12-2.17.
• a PVC moulding composition consisting of 100 parts by weight of a VCEVA commercial product (EVA-content 6% by weight, K value 69), 2.5 parts by weight of a solid barium/cadmium complex stabilizer (at least 10% Cd content), 1 part by weight of epoxidised soybean oil, 0.4 parts by weight of an organic phosphite, 0.2 parts by weight of oxystearic acid, 0.3 parts by weight of wax ester, 3.5 parts by weight of titanium dioxide and 2.5 parts by weight of calcium carbonate is processed in a heating-cooling mixer (1500 r.p.m.) into a pourable, homogeneous powder mixture (dry blend) according to the processing methods conventional for rigid PVC.
• a heating-cooling mixer (1500 r.p.m.
• a PVC moulding composition consisting of 100 parts by weight of a VCEVA-laboratory graft product (EVA content 6% by weight; content of polysiloxane B 0.51% by weight; K value 66), stabilizers, lubricants, pigments and fillers as described in Example 2.18 is prepared as described in Example 2.18.
• VCEVA-laboratory graft product EVA content 6% by weight; content of polysiloxane B 0.51% by weight; K value 66
• stabilizers, lubricants, pigments and fillers as described in Example 2.18 is prepared as described in Example 2.18.
• the mixture is stirred for 5 hours at room temperature to dissolve the solid substances and polymerization is then carried out by heating for 15 hours at 60° C.
• These powder mixtures (2.18, 2.19, 2.20) are extruded into a window profile on a double-screw extruder with a screw diameter of 85 mm and a 17D screw length, using a profile tool, consisting of a nozzle and a three-part vacuum calibration.
• Test bodies are taken from the extruded profiles for the following tests:
• the content of 0.5% by weight of polysiloxane C or 0.51% by weight of polysiloxane B in EVA-modified rigid-PVC moulding compositions produces substantially lower shrinkage values in the extruded profiles. This shrinkage reducing effect is furthermore not lost by the increase in the composition temperature from 186° C. to 196° C.
• Table VI clearly shows that, by adding the polysiloxane, the resistance of the moulding composition to a loss of strength during mechanical strain on the roller is substantially increased.
• the polysiloxane-free Comparative Example only has a notched impact strength of 8 kJ/m 2 after a 6 minute roll time
• the modified samples have results of 22 kJ/m 2 or 30 kJ/m 2 or 30 kJ/m 2 and they still retain their high notched impact strength with 19 kJ/m 2 after an 8 minute roll time at 175° C.
• the material extruded at 196° C. composition temperature also has substantially higher notched impact strengths at roll times of 4, 6 and 8 minutes, in contrast to the identically treated polysiloxane-free sample.
• a PVC moulding composition consisting of 90 parts by weight of suspension PVC with a K value of 65, 10 parts of a chlorinated polyethylene having a chlorine content of 36% by weight and a reduced viscosity of 1.6 dl/g (measured on a 0.5% solution in tetralin at 135° C.), 2.5 parts by weight of a solid barium/cadmium complex stabilizer (at least 10% Cd content), 1 part by weight of epoxidised soybean oil, 0.4 parts by weight of an organic phosphite, 0.2 parts by weight of oxystearic acid, 0.2 parts by weight of wax ester, 3.5 parts by weight of titanium dioxide and 2.5 parts by weight of calcium carbonate, is processed into a pourable dry blend in a heating-cooling mixer (1500 r.p.m.) according to the preparation methods conventional for rigid PVC.
• a heating-cooling mixer (1500 r.p.m.

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• 1980
  • 1980-11-03 DE DE19803041231 patent/DE3041231A1/de not_active Withdrawn
• 1981
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  • 1981-10-22 EP EP81108680A patent/EP0051770B1/de not_active Expired
  • 1981-10-28 US US06/315,620 patent/US4381361A/en not_active Expired - Fee Related
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